Medical devices such as pacers and defibrillators typically include at least one lead assembly. In a defibrillator, for example, a lead assembly typically includes at least one defibrillation electrode, such as a defibrillation coil. Some lead assemblies include a cover that extends over at least a portion of the outer surface of the lead assembly. A cover may extend over a defibrillation coil, for example. Covers are used, for example, to prevent tissue ingrowth.
United States Published Patent Application No. 2003/0023294A1 describes an expanded polytetrafluoroethylene (ePTFE) cover. Expanded polytetrafluoroethylene has a high melting point (over 300 degrees C.) and a high melt viscosity. The application of an ePTFE cover to a defibrillation electrode can involve sintering at high temperatures. Improved coverings for lead assemblies are needed.